Gerhard Brügmann

Curt Engelhorn Zentrum Archäometrie | CEZ Archäometrie

This study focuses on the origin of the Os isotope heterogeneities and the behaviour of Os and Re during melt percolation and partial melting processes in the mantle sequence of the Troodos Ophiolite Complex. The sequence has been divided into an eastern (Unit 1) and a western part (Unit 2) (Batanova and Sobolev, 2000). Unit 1 consists mainly of sp...

The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe–Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs in some samples as a late magmatic phase. Liquidus t...

The reference material (RM) UB-N is a typical representative of earth's upper mantle. It is a serpentinized garnet and spinel-bearing peridotite (a metamorphosed lherzolite) from the Vosges mountains, France, that is well characterized for major and many trace elements.In order to test whether UB-N is a suitable Re–Os reference material, 32 digesti...

The Re-Os isotopic system has been shown to provide a unique view of mantle processes that contrasts markedly with that provided by lithophile element isotope systems. In this study, Re and Os abundances and the Os isotopic composition of peridotites from the Zermatt-Saas ophiolite (ZSO) have been determined in order to asses the behaviour of these...

Alaskan-type, zoned mafic-ultramafic complexes occur along a chain extending over 900 km from the Central to the Northern Urals. A systematic Sm-Nd and Re-Os isotope study focuses on three questions: 1) what is the age relationship of the mafic and ultramafic intrusions of the Alaskan-type massifs in the Middle Urals, 2) what is the chemical compos...

Combined siderophile and lithophile element systematics in mantle rocks can be used to monitor melt percolation processes in the Earth’s mantle. Here we present a coherent dataset from a single melt channel from the mantle section of the Troodos Ophiolite Complex on Cyprus. The melt channel is composed of a dunite vein that is surrounded by harzbur...

We are investigating the extent to which crystal fractionation/crustal assimilation has affected the segregation of Platinum Group Elements in Deccan Traps. A series of picrites and basalts from the Deccan Traps were examined for Re-Os isotopes along with PGE contents. The samples cover a range of compositions from picrites with up to 22.4 wt.% MgO...

A petrological study was carried out on Mg-skarn-bearing dunite cumulates that are part of the Neo-Proterozoic Ioko-Dovyren intrusion (North Baikal region, Russia). Skarn xenoliths contain brucite pseudomorphs after periclase, forsterite and Cr-poor spinel. Fine-grained forsterite-spinel skarns occur with the brucite skarns or as isolated schlieren...

Melt-mantle interaction is monitored by Os isotopes, PGE abundances, REE in cpx and Cr# in spinel in a single melt channel of the mantle section from the Troodos Ophiolite Complex. The melt channel is composed of a central dunite (6 cm wide) which is surrounded by harzburgite. In both lithologies spinel has a Cr# of 0.58 +/- 0.01. Cpx in the dunite...

Mg-skarns enclosed in dunite cumulates of the Neo-Proterozoic Ioko-Dovyren intrusion (northern Baikal region, Russia) can be traced to silica-poor dolomitic host rock layers. The dominant minerals of the skarns are brucite (pseudomorph after periclase), forsterite and Cr-poor spinel. Rapid heating of quartz-poor dolomitic xenoliths led to the forma...

The Re–Os data on Archean komatiites from the Kostomuksha greenstone belt in the Baltic Shield are presented. This greenstone belt has been previously interpreted to represent a former oceanic plateau formed by the emplacement of an ancient plume head [Puchtel et al., Earth Planet. Sci. Lett. 155 (1998) 57–74]. Samples of flowtop breccia, spinifex-...

The Vetreny belt in the southeast Baltic Shield is a large volcano-sedimentary basin containing a 4- to 8-km-thick sequence of basaltic to komatiitic lavas, which were erupted 2.45 Ga ago in a continental rift setting during the interaction of a mantle plume and the Archean continental crust of the Karelian granite-greenstone terrane. Re-Os isotope...

The platinum-group elements (Os, Ir, Pt, Ru, Rh, and Pd) are highly siderophile and chalcophile elements, which are compatible elements and show similar geochemical behaviours. This group of elements includes two radiogenic isotope decay systems of 190Pt-186Os and 187Re-187Os. Recently, the application of PGEs and Re-Os isotope systems in the study...

The Palaeoproterozoic Ni–Cu sulphide deposits of the Pechenga Complex, Kola Peninsula, occur in the lower parts of ferropicritic intrusions emplaced into the phyllitic and tuffaceous sedimentary unit of the Pilguj a ¨ rvi Zone. The intrusive rocks are comagmatic with extrusive ferropicrites of the overlying volcanic formation. Massive lavas and chi...

We present Re–Os, Sm–Nd and Pb–Pb isotope and trace element data for the Konchozero sill, a layered mafic–ultramafic intrusion in the Early Proterozoic Onega plateau, one of the oldest continental flood basalt provinces on Earth. The Sm–Nd and Pb–Pb combined mineral and whole-rock isochron ages of 1988±34 and 1985±57 Ma for the sill coincide with t...

Drilling during ODP Leg 158 took place on the active mound of the TAG hydrothermal field on the Mid-Atlantic Ridge. The dominant mineral precipitating from the hydrothermal fluid is pyrite. Its Re and Os concentration and the Os isotopic composition provide constraints on the nature of the hydrothermal fluid circulating in the TAG mound. The 187Os/...

The Lac des Iles area is located in the Wabigoon Subprovince, an Archean granite-greenstone terrain in the Superior Province in Ontario, Canada. The area consists of several unmetamorphosed plutons of biotite- and hornblende-tonalite and mafic and ultramafic intrusions which are emplaced into an older tonalitic gneiss.The mafic/ultramafic bodies ar...

The elevated concentrations of noble metals in sulfide deposits of various types, volcanic exhalations, and volcanogenic-sedimentary rocks indicate that magmatic fluids are important in mobilizing, transporting, and concentrating these metals in magmatic and postmagmatic processes. The composition of volcanic gases and minerals accompanying platinu...

THE hydrothermal circulation of sea water through permeable ocean crust results in rock-water interactions that lead to the formation of massive sulphide deposits. These are the modern analogues of many ancient ophiolite-hosted deposits(1-4), such as those exposed in Cyprus. Here we report results obtained from drilling a series of holes into an ac...

Baddeleyite from Palabora Igneous Complex, South Africa, is among the purest natural ZrO2 phases. This has been demonstrated by using various methods, i.e. microprobe, neutron activation, spark source and thermal ion mass spectrometry. HfO2 with 1.87% is the only other major component. The concentrations of other HFSE are also relatively high, comp...

Experiments have been conducted on the partitioning of noble metals in the presence of an H-O-C-S fluid in a high pressure gas apparatus at 1200-1300°C and 1-4 kbar fluid pressure. The fugacities of oxygen and sulfur, and the chemical species in the fluid phase, were controlled by the presence of graphite and of a sulfide melt of pyrrhotite composi...

In this study Cu, Ni, and platinum-group elements (PGE) were determined in a sequence of basaltic and picritic lavas from the Siberian Trap in the Noril'sk area of Russia to constrain genetic relationships between the basalts and the petrogenesis of Ni-Cu-PGE sulfide deposits associated with the Talnakh and Noril'sk intrusions.In the most primitive...

A sensitive radiochemical technique is described, which allows the simultaneous analytical determination of the platinum-group elements Pd, Pt, Ir, Os and Ru, as well as Au, Se, As, Re and Sb, in common silicate rocks.About 100 mg of finely ground powder is irradiated with different neutron fluxes, either at the SLOWPOKE reactor (University of Toro...

The Dumont Sill is an Archaean komatiitic intrusion, whichDuke (1986) subdivided into a mafic (MZ) and ultramafic zone (UMZ). The UMZ comprises an upper (UPZ) and a lower peridotite subzone (LPZ) consisting of olivine + chromite cumulates and a dunite subzone (DZ) between them, consisting of olivine ± sulfide cumulates. Three sulfide-rich layers in...

The Lac des Iles Complex is a 2.74Ga-old composite intrusion emplaced into a granite and/or granite-gneiss terrane of the Wabigoon subprovince. The complex consists of a gabbroic and ultramafic part; the latter has been subdivided into northern and southern intrusive phases. Both the gabbroic and ultramafic parts contain platinum-group element-bear...

The Lac des Iles composite intrusion is subdivided into northern ultramafic and southern gabbroic complexes. Field evidence indicates that both mafic and ultramafic magmas coexisted with felsic magma of tonalitic composition. Platinum-group element (PGE)-rich, Ni-Cu sulphides are found in ultramafic and mafic rocks throughout the intrusion; the onl...

The distribution of the chalcophile and siderophile metals Cu, Ni, Au, Pd, Ir, Os and Ru in an Archaean komatiite flow from Alexo, Ontario and in a Phanerozoic komatiitic suite of Gorgona Island, Colombia, provides new information about the geochemical behaviour of these elements.Copper, Au and Pd behave as incompatible elements during the crystall...

The Circum-Superior Belt of Proterozoic basalts and sedimentary rocks surrounds, and in some places, unconformably overlies the Archaean Superior Craton in northern Quebec, Canada. Four main groups of volcanic rocks are recognized. The oldest unit, the Eskimo Formation on the Belcher Islands, consists of subaerial massive continental tholeiites wit...

preservation of refractory domains in the asthenospheric mantle rather than their erasure by mantle convection. The refractory domains would not be sampled by mid-ocean-ridge basalts because they contribute little to the genesis of magmas. We thus suggest that the upwelling mantle beneath mid-ocean ridges is highly heterogeneous, which makes it dif...

The solubility of platinum was determined in synthetic basalts of diopside/anorthite dry eutectic composition (An42Di56), with varying water contents (1wt% to saturation) at 1250^oC and 0.2 GPa. Experiments were conducted using a sealed capsule technique in internally heated pressure vessels equipped with a rapid quench device. The rapid quench dev...

Uralian-Alaskan-type mafic-ultramafic complexes are part of a belt that extends over 900 km from the middle to the northern Ural Mountains in Russia. Our study focuses on Os isotope systematics and the PGE geochemistry in 2 complexes: the Uktus Complex near Yekaterinburg and the Kytlym Complex about 250 km to the North of it. C1-chondrite-normalize...